on the outside vs outdoors

on the outside

prep
  • Not in prison 

  • On the outer surface 

  • To outward appearances 

outdoors

adv
  • Not inside a house or under covered structure; unprotected; in the open air. 

noun
  • The natural environment in the open air, countryside away from cities and buildings. 

  • The environment outside of enclosed structures. 

How often have the words on the outside and outdoors occurred in a corpus of books? (source: Google Ngram Viewer )